A head/disk testing apparatus is an apparatus for testing a head or disk used in a hard disk drive. Head/disk testing apparatuses comprise a spin stand, an electric measurement part, and a control part for controlling the spin stand and the electric measurement part. The spin stand comprises a disk rotating apparatus for rotating the disk and a positioning apparatus for relative positioning of the disk and the head.
It is specified that the head is positioned and measured at a pre-determined place on the disk during testing. This pre-determined place is one or more positions with different head read-write properties and becomes the reference place for measurement. The pre-determined place is, for instance, near the inner periphery of the disk, near the outer periphery of the disk, and so forth. Positioning at such a pre-determined place is called static positioning. Static positioning requires a wide positioning range of several 10 mm or more, but high speed is not required. Moreover, there are cases even during actual measurements where the head is finely relatively positioned. For instance, by means of track profile measurements, magnetic signals are written at a pre-determined place on a disk and then, the intensity of the magnetic signals that have been written is measured while continuously positioning in very small intervals close to the pre-determined place in order to measure the intensity distribution of these magnetic signals. This type of positioning during measurements is called dynamic positioning. Dynamic positioning requires high speed, but the necessary positioning range is 1 μm or less.
There are several types of head positioning apparatuses depending on the positioning system that is used. The X-Y system and the X-θ system are likely to be used in the positioning apparatuses.
Conventional X-Y positioning apparatuses comprise an XY stage and a piezo stage (for instance, JP (Kohyo) 2003-515,859 (page 7, FIG. 1)). The XY stage is an apparatus for linear positioning of a head in two orthogonal directions. The piezo stage is an apparatus for linear positioning of a head in a single direction. Static positioning is performed by the XY stage. Moreover, dynamic positioning is performed by the piezo stage.
In addition, a conventional X-θ positioning apparatus comprises an X stage and a rotary positioner (for instance, JP (Kokai) 2000-187,821 (FIG. 1)). The X stage is an apparatus for linear positioning of a head in a single direction. The rotary positioner is an apparatus for rotational positioning of a head. Static positioning is performed by the X stage and the rotary positioner. A means for moving the head in a total of three directions, the X direction and the Y direction of the XY stage and one direction of the piezo stage, is needed with the X-Y positioning apparatus. On the other hand, X-θ positioning apparatuses should have a means for moving the head in a total of two directions, the X direction of the X stage and the direction of rotation of the rotary positioner. Consequently, the X-θ positioning apparatus is characterized in that a means for movement of the head in one direction can be omitted and therefore, its physical size is small and apparatus cost is inexpensive when compared to the XY positioning apparatus.
However, the X-θ positioning apparatus has a disadvantage in that positioning speed is slow. The reason for this is explained below. The X stage and the rotary positioner of a conventional X-θ positioning apparatus are controlled by a PC. This is because controlling the X stage and the rotary positioner requires multiple complex processes. For instance, static positioning is performed by the X stage and the rotary positioner. An operation whereby coordinates (radius r, skew angle φ) designated by the user are converted to coordinates (x, θ) appropriate for control of the X stage and the rotary positioner before actual positioning is necessary with this static positioning. Moreover, by means of static positioning, the movement path of the head is found before actual positioning so that the moving head does not collide with obstructions. Furthermore, the X stage and the rotary positioner also perform head loading/unloading, and so forth. As previously mentioned, multiple complex processes are necessary for the X stage and the rotary positioner. When these processes are executed by a low-level processor such as a digital signal processor (DSP), or are fully hardware-implemented, the equipment structure and programs become complicated. Complex equipment structure and programs invite an increase in development manpower and development time. There has been considerable progress in technology in the hard disk drive field in recent years and there is an urgent market demand for excellent head/disk testing apparatuses. Moreover, there is a strong demand for a reduction in the cost of head/disk testing apparatuses in order to reduce the manufacturing cost of hard disk drives. In order to respond to the above-mentioned market demands, the X stage and the rotary positioner of the X-θ positioning apparatus are controlled using a PC with an ordinary OS loaded. However, this type of PC lacks real-time processing capability, such as frequent interruption of the OS. Dynamic positioning by the rotary positioner is limited by the PC processing capability and impedes high speed.
In addition to the above-mentioned demands, there has been a need for curtailment of testing time and reduction of equipment space for head/disk testing apparatuses in recent years. However, head/disk testing apparatuses comprising conventional positioning apparatuses cannot simultaneously satisfy these demands.
Therefore, the present invention uniquely provides a small-footprint positioning apparatus that is capable of high-speed positioning. Moreover, the present invention also provides a controlling apparatus for controlling this positioning apparatus.